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From: | Daniel Henrique Barboza |
Subject: | Re: [PATCH] spapr_numa.c: fixes in spapr_numa_FORM2_write_rtas_tables() |
Date: | Wed, 22 Sep 2021 08:50:53 -0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 |
On 9/22/21 08:17, Philippe Mathieu-Daudé wrote:
On 9/21/21 21:43, Daniel Henrique Barboza wrote:This patch has a handful of modifications for the recent added FORM2 support: - there is no particular reason for both 'lookup_index_table' and 'distance_table' to be allocated in the heap, since their sizes are known right at the start of the function. Use static allocation in them to spare a couple of g_new0() calls; - to not allocate more than the necessary size in 'distance_table'. At this moment the array is oversized due to allocating uint32_t for all elements, when most of them fits in an uint8_t; - create a NUMA_LOCAL_DISTANCE macro to avoid hardcoding the local distance value. Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com> --- hw/ppc/spapr_numa.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c index 58d5dc7084..039a0439c6 100644 --- a/hw/ppc/spapr_numa.c +++ b/hw/ppc/spapr_numa.c @@ -19,6 +19,9 @@ /* Moved from hw/ppc/spapr_pci_nvlink2.c */ #define SPAPR_GPU_NUMA_ID (cpu_to_be32(1)) +/* Macro to avoid hardcoding the local distance value */ +#define NUMA_LOCAL_DISTANCE 10 + /* * Retrieves max_dist_ref_points of the current NUMA affinity. */ @@ -500,17 +503,21 @@ static void spapr_numa_FORM2_write_rtas_tables(SpaprMachineState *spapr, MachineState *ms = MACHINE(spapr); NodeInfo *numa_info = ms->numa_state->nodes; int nb_numa_nodes = ms->numa_state->num_nodes; + /* Lookup index table has an extra uint32_t with its length */ + uint32_t lookup_index_table[nb_numa_nodes + 1]; int distance_table_entries = nb_numa_nodes * nb_numa_nodes; - g_autofree uint32_t *lookup_index_table = NULL; - g_autofree uint32_t *distance_table = NULL; - int src, dst, i, distance_table_size; - uint8_t *node_distances;This should have be of ptrdiff_t type.+ /* + * Distance table is an uint8_t array with a leading uint32_t + * containing its length. + */ + uint8_t distance_table[distance_table_entries + 4];The previous code seems better by using the heap, now we have to worry about stack overflow...
Fair point. Since no one asked for this change in previous reviews I guess it's fine to keep using the heap. Daniel
+ uint32_t *distance_table_length;Please drop, ...+ int src, dst, i; /* * ibm,numa-lookup-index-table: array with length and a * list of NUMA ids present in the guest. */ - lookup_index_table = g_new0(uint32_t, nb_numa_nodes + 1); lookup_index_table[0] = cpu_to_be32(nb_numa_nodes); for (i = 0; i < nb_numa_nodes; i++) { @@ -518,8 +525,7 @@ static void spapr_numa_FORM2_write_rtas_tables(SpaprMachineState *spapr, } _FDT(fdt_setprop(fdt, rtas, "ibm,numa-lookup-index-table", - lookup_index_table, - (nb_numa_nodes + 1) * sizeof(uint32_t))); + lookup_index_table, sizeof(lookup_index_table))); /* * ibm,numa-distance-table: contains all node distances. First @@ -531,11 +537,10 @@ static void spapr_numa_FORM2_write_rtas_tables(SpaprMachineState *spapr, * array because NUMA ids can be sparse (node 0 is the first, * node 8 is the second ...). */ - distance_table = g_new0(uint32_t, distance_table_entries + 1); - distance_table[0] = cpu_to_be32(distance_table_entries); + distance_table_length = (uint32_t *)distance_table; + distance_table_length[0] = cpu_to_be32(distance_table_entries);... and use instead: stl_be_p(distance_table, distance_table_entries);- node_distances = (uint8_t *)&distance_table[1]; - i = 0; + i = 4; for (src = 0; src < nb_numa_nodes; src++) { for (dst = 0; dst < nb_numa_nodes; dst++) { @@ -546,18 +551,16 @@ static void spapr_numa_FORM2_write_rtas_tables(SpaprMachineState *spapr, * adding the numa_info to retrieve distance info from. */ if (src == dst) { - node_distances[i++] = 10; + distance_table[i++] = NUMA_LOCAL_DISTANCE; continue; } - node_distances[i++] = numa_info[src].distance[dst]; + distance_table[i++] = numa_info[src].distance[dst]; } } - distance_table_size = distance_table_entries * sizeof(uint8_t) + - sizeof(uint32_t); _FDT(fdt_setprop(fdt, rtas, "ibm,numa-distance-table", - distance_table, distance_table_size)); + distance_table, sizeof(distance_table))); } /*
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